Friday, August 13, 2010

DIC image of Nucleolinus within the surf-calm, spisula (right) oocyte.

Surprise, Surprise! In the ripe age of satellite imagery and femto-scale probes, when folks are busy tweezing protein surfaces, these guys have (re)-discovered a cell-organelle. Perhaps, it's akin to the discovery of a new continent in the age of the terrace-pervading 'google-earth'.

Folks from the Marine Biological Laboratory's (MBL) Josephine Bay Paul Center, at the University of Illinois present their discoveries regarding the "Nucleolinus" in a paper in the Proceedings of the National Academy of Sciences (PNAS).
Although the nucleolinus, a cellular structure observed in the nucleus of many cells, including invertebrate egg cells and some mammalian cells, was discovered (and forgotten) more than 150 years ago, and other scientists had proposed its involvement in cell division, difficulties in visualizing the nucleolinus inside most cells had kept further studies at bay.
The scientists went on to develop a ribo-probe - NLi-1 for the RNA molecule present exclusively in the nucleolinus compartment in the oocytes of the surf clam, Spisula solidissima (the unfortunate clam is a valued delicacy in some cultures!). This breakthrough development of a marker for the elusive organelle would now serve the purpose of a beacon, and make future studies into its relevance and consequence in cells easier.
Other in situ observations in the oocytes revealed that the nucleolinus (and NLI-1) were inseparably associated with the developing spindle and centrosomes, and therefore could be related to cell-division.

Laser microsurgery that targeted the nucleolinus resulted in failed meiotic cell division in parthenogenetically activated oocytes and failed mitosis in fertilized oocytes, hence acribing a definitive role to the Nucleolinus in cell-division.

This investigation could clarify recent studies indicating an important role for the nucleolus in cell division. Possibly it was the shy Nucleolinus, all the way!

Curiously, the paper's bibliography cites references from as further back as 1857! (We, Indians were busy fighting the 1st war of independence against imperialist marauders then...)..

References:

* Alliegro, M.A., Henry, J.J., Alliegro, M.C. Rediscovery of the Nucleolinus, a Dynamic RNA-Rich Organelle Associated with the Nucleolus, Spindle, and Centrosomes. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1008469107